Draft equalizing stack head



Feb. 15, 195s i w; Q MORAN y 2,101,999

DRAFT EQUALIZING STACK HEAD 2 sheets-sheet 1 @U2/19 /7 li Filed Oct. 7,1952 woo www

" william amm Feb. 15, 1955 w. o. MoRAN 2,701,999

DRAFT EQUALIZING STACK HEAD Filed Oct. 7, 1952 I I 2 Sheets-Sheet 2Siwa/YM /Vllam 0. Moran im 5M M 77;@

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Un'ited States Patent() 1mm EoUALiziNG sucx imap william o. Mom, misa,om.

Applicatie.. ociober 1, 1952, semi No. 313,568

s claims. (ci. 9s-ss) This invention relates to improvements in thestructure of the stack head of chimneys and exhaust stacks to providefor equalizng the draft therein regardless of outside wind conditions.This invention is a continuation-inpart of mycopending applicationSerial No. 54,451 filed October 14, 1948, now U. S. Patent 2,655,833,issued October 27, 1953, said copending application being a continuationof applicants application Serial No. 689,231, filed August 8, 1946, nowabandoned.

It`is the object of my invention to provide a stack head structure thatwill eliminate draft fluctuationcaused by wind direction and forcechanges thus providing a controlled draft resulting in increasedeticiency of the boiler or heater which discharges into an exhaust stackor chimney having a stack head structure according to my invention. l

A further object of my invention is to provide a head structure in achimney or exhaust stack that will keep the draft constant and hold thefre in the fire box of the boiler or furnace connected thereto.

Another object of my invention is to provide a chunney or exhaust stackfor a boiler or furnace which is constructed with its top endimperforate but having the adjacent vertical side walls there belowpierced with a plurality of orifices or ports preferably in uniformspaced relationships and having suicient area to permit free movlment ofexhaust gases from the chimney or exhaust stac Another object of myinvention is to provide a cap for telescopic mounting into or onto thetop end of a chimney or exhaust stack of a boiler or furnace wherein thecap is constructed with an imperforate top end but has the adjacentvertical side walls there below pierced with a plurality of orifices orports preferably in uniform spaced relationships and having sufficientarea to permit free movement of exhaust gases from the chimney orexhaust stack.

A still further object of my invention is to provide a heating unit withan equalizng stack head in order to maintain an equalized or uniformdraft, and prevent downdraft, regardless ofthe direction and amount ofwind pressure that may occur at the stack head.

Another object of my invention is to provide a ventilator for any typeof structure where ventilation is needed but where excessive ventilationis undesirable, such as would be caused by high winds blowing across theconventional type of ventilator. This type of ventilation is especiallydesirable in carbon black plants, paint rooms, battery rooms, and manyother places where a constant steady draft is required.

These draft equalizng stack heads, when used as ventilators can beinstalled on trucks, planes, trains, or ships, as the speed of theconveyance, plus the speed of the wind, will not change the draftthrough these stack heads.

Other objects and advantages of the invention will be evidient from thefollowing detailed description read in conjunction with the accompanyingdrawings.

ln a chimney or stack head having the usual end opening of area equal tothe cross sectional area of the end of the stack, increased windpressure from any direction blowing over the open top end of the stackcauses a suction upward in the stack and pulls lthe fire from the firebox. This action causes a demand for more fuel and the draft is somewhatproportional to the wind pressure. However, according to my inventionwith a chimney head provided with a closed top with adjacent walls therebe- 2,701,999 Patented Feb. 15, 1955 ICC low havin spaced holestherethrough of suticient s rea to permit re movement of exhaust gasesfrom the chimney or exhaust stack, there is created a uniform draft inthe stack regardless of wind velocity or direction. It is thought thatthe vacuum-created in such a construction by the action of the wind onthe down wind side of the stack is offset by wind blowing from the upwind side of the stack that passes through the apertures in the stacksupplying air to counteract the vacuum created on the opposite side ofthe stack. This action of the windpassing through the apertures on theWindward side of the stack offsets the vacuum normally created on theleeward or down wind side of the stack and this action serves to createa uniform draft in the stack and fire box regardless of the wind forceor direction.

When the wind begins to blow against the stack head, it shortens theflow-of the stack gases on the upstream, or Windward, side of the stack,but it lengthens the ow of stack gases on the downstream side of thestack. As the wind increases in velocity across the stack head, the flowof stack gases on the upstream side continues to shorten, and the flowof stack gases on the downstream side continues to lengthen, until suchtime as the wind pressure and the pressure 'of the stack gases areequal. At this point, the openings in the upstream side are effectivelysealed off because with wind pressure on the outside of the stack beingequal to the pressure of the stack gases on the inside of the stack, nowind can blow into the stack, nor can any of the stack gases escape fromthe stackon the upstream side. When the wind pressure exceeds the stackpressure, the wind blows through the openings on the upstream side,which supplies the excess demand created by the lessening of pressure,or by the vacuum created on the downstream side, which permits a fasterflow of the stack gases through the openings, in the downstream side ofthe stack.

It has been proven by many extensive tests that the velocity of the windblowing through the stack head does not change the velocity or theamount of stack gases pulled through the fire box of the boiler; thus,maintaining still day efiiciency of heating equipment regardless of thevelocity of the wind.

My invention may be used on exhaust stacks of heaters for meter houseswhich are frequently erected in isolated and exposed places where theymay be subjected to winds which blow from every direction of the compassand over a large range of wind velocities. A heater for such an exposedmeter house must be capable of functioning continually without beinginfluenced by variations in wind directions and velocity, andparticularly without being extinguished by sudden changes in directionof the Wind and its velocity.

For a more complete understanding of the nature and scope of myinvention reference may be had to the accompanying drawings in which:

Fig. 1 is a perspective view according to my invention;

Fig. 2 is a vertical cross sectional view along lines 2 2 of Fig. l butshowing the open bottom end of the cap teleskcopically received over theopen end of an exhaust stac Fig.- 3 is a cross sectional view showingthe cross section of the cap as viewed along line 3 3 in Fig. 4;

Fig. 4 is a schematic drawing of a cross section of a of a draftequalizer cap heatei having a draft equalizer stack head or capinstalled on the exhaust stack according to my invention;

Fig. 5 is a perspective view looking upward from a position adjacent thebottom end showing a modified form of draft equalizng cap or stack headmounted within the top of a top fragmentary end of a stack;

Fig. 6 is a cross sectional view of the modified form taken on line 6 6of Fig. 5; and

Fig. 7 is a cross sectional view taken along lines 7 7 of Fig. 6 of themodified form of cap or stack head.

Throughout the various views in the drawing like reference numeralsrefer in similar parts.

In Fig. 4 a typical heater, furnace, boiler or the like is indicated at10 having a fire box l1 provided with a burner 12 over which ispositioned a horizontal baille 13 providing an exhaust chamber 14 havinga vertical exhaust stack or chimney l attached thereto on the upperportion of the heater or furnace.

I mounted on the upper end of the exhaust stack or chimney 15 a draftequalizing head or cap generally indicated at 16.

The cap 16 in the embodiment here illustrated is of elongatedcylindrical shape having a vertical wall 17, an open bottom end 18telescopicallv received over the end 15' of the stack 15, and animperforate top end 19. The wall 17 is pierced with a plurality ofapertures 20 extending therethrough, preferably equally spaced andhaving suicient area to permit free movement of exhaust gases from thechimney or exhaust stack. These apertures 20 are positioned all aroundthe whole wall area 17. At the lower end 19' of the cap 16 adiacent theopen bottom 18 there may be positioned a plurality of equally spacedthreaded apertures 22 which receive threaded tap screws 23 to secure thecap 19 in the upper end 15 of the exhaust stack 15.

While l have here shown the apertures 20 as being t circular they may beof any configuration, circular apertures being here shown and used asthey are more easily provided.

Tn Figures l and 2 it will Abe noted that thereare seven horizontal rowsof apertures 20 spaced substantiallv at a uniform distance apart alongthe elongated vertical wall 17 of cap 16. There are an even number ofapertures in each row, namelv. twelve apertures having a uniform `eclualarea. The apertures 20 are disposed in uniformly spaced relationshipthroughout the whole circumference of the cap 16. Each of the apertures20 is disposed in each horizontal row so that each aperture has anoppositelv disposed aperture in horizontal alignment therewith. Thissame arrangement of apertures applies to the structure shown in Figures5, 6 and 7. except that each horizontal row in the cap or stack head 29has an even number of -fourteen apertures 30.

The exhaust stack 15 may equally as well be a bricked uo chimney and .insuch a case I carry out my invention bv laving up the head of thechimney with an apertured wall having the total aperture area sufficientto permit the free movement of exhaust gases from the tue or chimnev. lnlaying up a brick chimney, I would provide an imoerforate top end 19 asI have in the cap 16 here illustrated.

I have shown in Fig. 2 arrows P to represent the wind blowing against anarea at the left hand portion of the cap 16 while at the opposite area.arrows V represent a vacuum created about the opposite area of the cap.The arrows designated S within the exhaust stack 15 represent thesuction existing in the ue of the exhaust stack or chimnev. This suctionremains stable even though the pressure of the wind at P may increase ordecrease and the corresponding vacuum represented by the arrows V mavincrease or decrease. The wind is permitted to pass through theapertures 20 in the area of the blowing wind P and it is thought tooffset the vacuum created at V at the opposite area of the stack head orcap, thereby not disturbing the suction within the exhaust ue.

In a beater such as is used in meter houses in the oil fields which havea 3" diameter stack of 7 feet in length, I have installed a 3" cap andmade certain tests. The pressure of the gaseous fuel supplied to theburner in the fire box was 6% ounces open pressure. Compressedair wasblown across the top of the heater stack without having an eoualizingcap installed and when the pressure of the compressed air in a 1A"blowing nozzle reached 20 pounds per square inch gauge pressure. theflame in the fire box was extinguished thereby. This condition of flameextinguishment existed when either butane or natural gas was used.

A draft eaualizing stack head according to my invention was theninstalled on the exhaust stack of the heater and further tests wereconducted after the burner was ignited in the lire box of the heater.The compressed air nozzle discharge was directed against the perforatedcap to simulate the blowing wind and the pressure was raised in thecompressed air line to 550 pounds per square inch gauge pressure. thehighest available, and the ame at the burner was not blown out.

Figures 5, 6 and 7 depict a modified form of cap or stack head generallyindicated at 29 which is adapted for telescopic reception within a stack15. The cap 29 1s of cylindrical shape and is provided with a pluralityof relatively small spaced apertures or orifices 30 in the wall 31thereof. The total area of the orices 30 may be ter than thecross-sectional area of the stack on which the head or cap is mounted.The same theory of operation as explained for the stack head 16, asillustrated in Figure 2, applies'as respects stack head 29.

The cap or stack head 29 is provided with an annular imperforate base 32which is attached as by welding to the top end of a cylindrical thimble33 adapted to be received by a telescopic slip tit in the topend of thestack or chimney 15 such that the imperforate annular base 31 rests onthe top end l5 of the stack 15. The upper end of the stack head or ca 29is closed off' by an imperforate top plate 34 attac ed as by welding.Imperforate top plate 34 is shoQwn as extending as an annular lip 34'beyond the cylindrical wall 31.

The cap or stack head 29 is held in place on the top end of the stack 15by its own weight, however, if desired securing means such as tap screws(not shown) may be inserted through suitable apertures (not shown)formed in the stack 15 and received in threaded apertures (not shown) inthe thimble portion 33 of the cap 29.

Draft equalizing stack heads according to my invention are useful inincreasing the elciency of operation in all types of furnace and boilerplant installations. As an example of increased efciency suchstack-heads were installed on a gasoline plant having nine oil fieldtype boilers. Prior to the installation of the draft equalizer stackheads or caps, the fuel consumption of these boilers was at the rate of1550 cu. ft. per rated boiler horse power per day under normal windageconditions. After the installation of the draft equalizing stack headsthe fuel consumption decrease from the 1550 cu. ft. ligure to 1220 cu.ft. per horse power per day, even under high wind conditions, thusresulting in a fuel saving of 20%.

Since it is obvious Ithat certain changes can be made in the foregoingconstructions without departing from theA spirit and scope of thisinvention, it is intended that all matter shown in the accompanyingdrawings or described herein before shall be interpreted as illustrativeand not in a limiting sense. l

I claim as my invention:

1. In a chimney, a vertical tubular wall forming a vertical ue therein,an imperforate top on said chimney, said wall adjacent said top forminga stack head and having a plurality of horizontally disposed rows ofapertures therethrough, said rows being spaced substantially uniformlyfrom each other, each horizontal row of apertures having an even numberof apertures disposed in uniformly spaced relationship throughout thewhole circumference of said stack head, each of said apertures being ofuniform area, said apertures being disposed in each horizontal row sothat each aperture has an oppositely disposed aperture in horizontalalignment therewith, the total area of said apertures being suicient topermit free movement of exhaust gases from the chimney as determined forstill day operating conditions for said chimney, whereby when wind blowsagainst one apertured portion of the stack head, the vacuum created atthe opposite apertured portion of the stack head is offset by the windowing through the apertures in the lirst portion to the alignedapertures in the-second portion, whereby the action of the windregardless of direction or velocity in acting on any apertured portionof the stack head does not change the uniform draft of still dayoperating conditions in said chimney.

2. In a chimney, a vertical tubular wall forming a vertical lluetherein, said wall adjacent said top forming a stack head and having aplurality of horizontally disposed rows of apertures therethrough, saidrows being spaced substantially uniformly from each other, eachhorizontal. row of apertures having an even number of apertures disposedin uniformly; spaced relationship throughout the whole circumference ofsaid stack head, each of said apertures being of uniform area, saidapertures being disposed in each horizontal row so that each aperturehas an oppositely disposed aperture in horizontal alignment therewith,the total area of said apertures .being sufficient to permit freemovement of exhaust gases from the chimney as determined-for still dayoperating conditions for said chimney, whereby when wind blows againstone apertured portion of the stack head,

regardless of direction or velocity in acting on any apertured portionof the stack head does not change the uniform draft of still dayoperating conditions in said vchimn chimney, said vertical tubular wallhaving a plurality of horizontally disposed rows of aperturestherethrough,

said rows being spaced substantially uniformly from each other, eachhorizontal row of apertures having an even number of apertures disposedin uniformly spaced relationship throughout the whole circumference ofsaid vertical tubular wall, each of said apertures being of uniformarea, said apertures being disposed in each horizontal row so that eachaperture has an oppositely disposed aperture in horizontal alignmenttherewith, the total area of said apertures being sufficient to permitfree movement of exhaust gases from the chimney as determined for stillday operating conditions for said chimney, whereby when wind blowsagainst one apertured portion of the draft equalizing stack head, thevacuum created at the opposite apertured portion of the stack head isoffset by the wind flowing through the apertures in the first portion tothe aligned apertures in the second portion whereby the action of thewind regardless of direction or velocity in acting on any aperturedportion of the stack head does not change the uniform draft of still dayoperating conditions in said chimney. 4. A draft equalizing stack headaccording to claim 3 including means for holding said stack head inadjustable position on the top of said chimney.

5. A draft equalizing stack head adapted to vertically surmount the flueof a chimney, said stack head having a vertical tubular wall forming aue therein, an open top end and an open bottom end, said open bottom endbeing adapted to be connected with the top ofthe chirnney so that the ueof the chimney is in communication with the flue of said stack head,means for securing said stack head to said chimney, said verticaltubular wall having a plurality of horizontally disposed rows of aper-`tures therethrough, said rows being spaced substantially uniformly fromeach other, each horizontal row of apertures having an even number ofapertures disposed in uniformly spaced relationship throughout the wholecircumference of said vertical tubular wall, each of said aperturesbeing of uniform area, said apertures being disposed in each horizontalrow so that each aperture has an oppositely disposed aperture inhorizontal alignment therewith, the total area of said apertures beingsufficient to permit free movement of exhaust gases from the chimney asdetermined for still day operating conditions for said chimney, wherebywhen wind blows against one apertured portion of the draft equalizingstack head, the vacuum created at the opposite apertured portion of thestack head is offset by the wind flowing through the apertures in thefirst portion to the aligned apertures in the second portion whereby theaction of the wind regardless of direction `or velocity in actng on anyapertured portion of the stack head does not change the uniform draft ofstill day operating conditions in said chimney.

6. A draft equalizing stack head according to claim 5 including meansfor holding said stack head in adjustable position on the top of saidchimney. D

7. -A draft stabilizing device for mounting in the top of a chimney toproject vertically upward from the chimney, comprising a thirnbleadapted to be telescopically received within the top end of the chimney,a transversely extending annular plate attached to the top end of saidthimble and extending transversely of the top of said chimof saidtransversely extending annular plate, and

ney and adapted to rest thereon, an annular vertically extendingelongated shell attached to the outer periphery an imperforate plateattached to and closing off the top end of said shell, the verticallyextending wall of said elongated shell having a plurality ofhorizontally disposed rows of apertures therethrough, said rows beingspaced substantially uniformly from each other, each horizontal row ofapertures having an even number of apertures disposed in uniformlyspaced relationship throughout the whole circumference of said elongatedshell, each of said apertures being of uniform area, said aperturesbeing disposed in each horizontal row so that each aperture has anopposite-l ly disposed aperture in horizontal alignment therewith, thetotal area of said apertures being sufficient to permit free movement ofexhaust gases from said chimney as determined for still day operatingcondition for said chimney with no wind blowing, whereby when wind blowsagainst one apertured portion of the elongated shell, the vacuum createdat the opposite apertured portion of the elongated shell is offset bythe wind owing through the apertures in the first apertured portion tothe aligned apertures in the second portion whereby the action of thewind regardless of direction or velocity in acting on any aperturedportion of the elongated hollow shell does not change the uniform draftof still day operating condition in said chimney.

8. A draft stabilizing device for mounting in the top of a chimney toproject vertically upward from the chimney, comprising a thirnbleadapted to be telescopically received within the top end of the chimney,a transversely extending annular plate attached to the top end of saidthirnble and extending transversely of the top of said chimney andadapted to rest thereon, an annular vertically extending elongated shellattached to the outer periphery of said transversely extending annularplate, the vertically extending wall of said elongated shell having aplurality of horizontally disposed rows of apertures therethrough, saidrows being spaced substantially uniformly from each other, eachhorizontal row of apertures having an even number of apertures disposedin uniformly spaced rela tionship throughout the whole circumference ofsaid elongated shell, each of said apertures being of uniform area, saidapertures being disposed in each horizontal row so that each aperturehas an oppositely disposed aperture in horizontal alignment therewith,the total area of said apertures being suflcient to permit free movementofv exhaust gases from said chimney as determined for still dayoperating condition for said chimney with no wind blowing,

whereby when wind blows against one apertured portion of the elongatedshell, the vacuum created at the opposite apertured portion of theelongated shell is offset by the wind flowing through the apertures inthe first apertured portion to the aligned apertures in the secondportion whereby the action of the wind regardless of direction orvelocity in acting on any apertured portion of the elongated hollowshell does not change the uniform draft of still day operating conditionin said chimney.

References Cited in the file of this patent UNITED STATES PATENTS363,236 Hodel May 17, 1887 544,390 Shannon Aug. 13, 18.95 1,222,794Quinn Apr. 17, 1917 1,930,050 Hilt Oct. 10, 1933 2,060,364 Chase Nov.10, 1936 2,381,178 Munyon Aug. 7, 1945 2,598,603 Richtarsic May 27, 19522,630,748 v Brockelsby Mar. 10, 1953 FOREIGN PATENTS 964,531 'FranceFeb. 1, 1950

